A showdown is taking shape between lawmakers who want an Active Protection System on the Ground Combat Vehicle and acquisition officials who say that’s not going to happen.

The House Armed Services Committee, in reports leading up to passage of its version of the 2014 National Defense Authorization Act, said the lack of an APS will “soon create a critical capability gap for Army combat vehicles due to the rapid proliferation of advanced anti-tank guided missiles and next-generation rocket propelled grenades.”

The Army was “encouraged” to establish and fund a program in fiscal 2015.

But don’t count on it.

“We won’t include an APS solution for GCV. It’s just too expensive,” said Lt. Gen. William Phillips, military deputy to the Army’s acquisition executive. “It will drive the cost of the vehicle to become unaffordable. An APS solution adds significant cost and, depending on what solution you get, it adds significant weight.”

Calling the weight into question may seem questionable since one GCV contender tips the scales at 70 tons, which matches the enhanced M1A2 tank and would make it the world’s heaviest infantry fighting vehicle. But much of that weight comes from armor packages that rest on a steel core hull to give maximum protection, officials said.

An APS takes a different approach. It protects the vehicle and crew from man-portable weapons such as rocket-propelled grenades and anti-tank missiles. The threat is identified, then destroyed by automated countermeasures.

The most notable APS is Israel’s battle-tested Trophy system. The Army planned to test Trophy in conjunction with the failed Future Combat Systems and had alluded to giving it consideration for GCV.

General Dynamics in May became the first company to complete a critical design review for an APS on a North American combat vehicle, a Light Armored Vehicle III demonstrator. Designers look to validate the system this year.

General Dynamics Land Systems is one of two competitors in the GCV competition. The other is BAE Systems Land & Armaments, which also has acquired APS technology — Artis’ Iron Curtain.

It is too early to tell whether the Army or Congress is likely to back down. But this is not the first time this year the $29 billion GCV program has been in Congress’ cross hairs — and it is likely not the last.

Congress fully funded the Army’s fiscal 2013 request of $639.9 million for research and development on the GCV. But lawmakers look to withhold funds for the engineering and manufacturing phase unless Army Secretary John McHugh submits an independent assessment of the Army’s plan to proceed into the EMD phase with one contractor.

The Government Accountability Office has warned that a down-select prior to the EMD phase could become expensive.

The GCV program also suffered hits from an April Congressional Budget Office report that said the vehicle should be replaced with the German Puma or an upgraded Bradley Infantry Fighting Vehicle. Both would be “significantly more capable than the GCV” and Pumas would cost $14 billion less, while upgraded Bradleys would save $9 billion, the report said.

Army leaders and the companies competing to build the GCV disputed the findings. They said the data is wrong.

Neither Puma nor the Bradley can move an entire squad. The German vehicle carries six soldiers, which means the Army would have to buy five Pumas for every four Bradleys it replaced. The Bradley carries seven soldiers. Nine soldiers comprise an Army squad.

The CBO report offered four options. Each falls short of the GCV in capability but would provide the Army with an improved vehicle at less cost and in less time. The options are:

■ Purchase the Israeli Namer APC. The armored personnel carrier has better survival rates than GCV and can carry a squad. But it lacks GCV’s lethality and mobility.

■ Upgrade the Bradley IFV. It would be more lethal than GCV and match its survivability. But the upgraded Bradley would carry only seven passengers and lack GCV’s mobility.

■ Purchase the German Puma IFV. CBO said Puma is the most lethal of the vehicles because it boasts a 30mm cannon, which is better than the GCV’s 25mm cannon. But GCV has been upgraded to a 30mm cannon, so this point is moot. Still, CBO contends Puma would match GCV’s mobility and beat its survivability, a position hotly contested by General Dynamics and BAE Systems.

■ Cancel the GCV. A reconditioned Bradley fleet could be maintained through 2030.

Don’t expect GCV to go down without a fight. Army leadership has long argued that the need for GCV is not just a matter of finances but fighting ability. And nothing, they say, can compare to GCV in that battle. The Army is convinced that GCV is the solution, and the vehicle remains the top priority in Army acquisitions.

The Army will spend more than 80 percent of its combat vehicle modernization budget on GCV over the next five years. That follows a loss of $14 billion on FCS.

The plan is to build roughly 1,800 GCVs to replace the Bradley. The first GCVs would enter production in 2018. That still means the first unit would not be equipped until 2022. It would be another 10 years before the Army was “pure fleet” in its armored brigades.